1. Field of the Invention
The present invention relates to container capping machines. The invention is particularly directed to a device for stabilizing container caps on their corresponding containers during installation of the caps by capping machines.
2. Description of the Prior Art
Capping machines, that use rotating rollers to threadably cap containers, have been in existence for over 40 years. The current method of capping containers may be seen in the applicant's in-line capping machine Model No. NEIL-C 46-16. This capping machine, as well as other similar machines, operates by advancing containers along a predetermined path while gripping the container to prevent its rotation. The open top of the container engages and strips a cap from a standard cap dispensing apparatus. When coming to rest on the container, the cap is frequently misaligned, for example, tilted to one side.
Two driven rollers are placed in a predetermined fixed position on opposing sides of the predetermined path of the container so that each roller simultaneously engages the container cap as the container passes between the driven rollers. These rollers rotate the cap causing threads on the cap to engage threads on the container. Rotation of a misaligned cap may not always cause the cap to straighten, resulting in the threads on the cap becoming cross threaded with the threads on the container. Also, if the cap is not properly seated upon the container prior to rotation of the cap by the rollers, the rollers may rotate the cap without immediate engagement of the cap threads with the container threads. This delay in engagement may result in a cap that is not tightly closed after passing between the last pair of cap tightening rollers, creating a defective product. When the container caps must be tighten to a predetermined torque, cross threading will create incorrect readings, indicating that the proper torque has been reached and proper closure obtained. This may occur even when multiple pairs of rollers are used. Adding additional rollers, to ensure closure has occurred, adds time and cost to the bottling process. While additional rollers may solve the problem of the delayed engagement of the threads at additional cost, they will not solve the cross threading problem. There is a need, therefore, for a device that ensures that the container cap is placed on the container so that it is square to the open end of the container and provides a slight downward pressure on the cap to ensure that the cap threads threadably engage the container threads as quickly as possible, improving the efficiency of the capping process and reducing the number of failures.